How do you solve -2cos^2 x = 3cosx + 1 and find all solutions in the interval (0,2π)?

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Answer 1 · 2018-05-01T02:24:37

#0 = (2 cos x + 1)(cos x + 1)#

#cos x = -1/2 or cos x = -1#

In the interval that's #{2pi}/3, {4pi}/3, {3pi}/2#

#0 = 2 cos ^2 x + 3 cos x + 1 #

#0 = (2 cos x + 1)(cos x + 1)#

#cos x = -1/2 or cos x = -1#

#x = \pm {2pi}/3 + 2pi k # for integer #k# or #x = -pi/2 + 2pi k #

In the interval that's #{2pi}/3, {4pi}/3, {3pi}/2#